In general, if a load of a power converter is, for example, an electric motor, a capacitance between the electric motor and the ground causes leakage current to flow from the electric motor through the capacitance to the ground along with an output of a pulse voltage in the power converter. To reduce the leakage current, according to the configuration adopted in, for example, Patent Document 1, compensation current has been allowed to flow to compensate for the leakage current only when the magnitude of an instantaneous value or peak value of a voltage across a coil through which a current of an alternating-current waveform corresponding to a leakage current detected by a leakage current detector or a monitor current proportional to the detected current flows exceeds a predetermined threshold.
According to the configuration adopted in Patent Document 1 described above, if a power factor improvement circuit provided for a power converter is on (specifically, the duty cycle of a built-in switching element is controlled), compensation current is allowed to flow. If the power factor improvement circuit is off (the built-in switching element is kept off), supply of compensation current is stopped. Thus, only a large leakage current allows the compensation current to flow, resulting in a reduction in power loss.